Mechanism for producing intermittent rotation



MECHANISM FOR PRODUCING INTERMITTENT ROTATION Filed June 5, 1967 2 Sheets-Sheet 1 INVENTOR. JOHAN van DER mnosn July 22, 1969 J. VAN DER MAADEN MECHANISM FOR PRODUCING INTERMITT'ENT ROTATION Filed June 5, 1967 2 Sheets5heet 2 INVENTOR. JOHAN VAN DER MAADEN United States Patent 3,456,521 MECHANISM FOR PRODUCING INTERMITTENT ROTATION Johan van der Maaden, Emmasingel, Eindhoven, Netherlands, assignor, by mesne assignments, to U.S. Philips Corporation, New York, N.Y., a corporation of Delaware Filed June 5, 1967, Ser. No. 643,652

Int. Cl. F16h 55/04 US. Cl. 74-436 8 Claims ABSTRACT OF THE DISCLOSURE A mechanism for producing intermittent rotation from a continuously rotating input. A disc mounted on a continuously rotating shaft has an axially projecting driving pin which engages and drives a Geneva wheel except when the disc is moved axially to interrupt the driving action. A locking element controlling the disc is actuated by the armature of an electromagnet, with an intermediary cam means to minimize motion and noise during movement of the locking element.

In a known driving mechanism of the said type, the driving pin is journalled in the rotating disk so as to be slidable axially; the locking element, by means of which the pin can be retained in a retracted position with respect to the Geneva wheel, is pivotably housed in the disk and consequently rotates with said disk. The magnet armature which actuates the locking element is arranged outside the disk and comprises a sloping surface for the locking element which surface, dependent upon the energizing of the magnet, can be moved in the path of the rotating locking element so as to uncouple the locking element relative to the driving pin. As a result of this the pin is made to engage the Geneva wheel under spring force, and the wheel is rotated one step further. After leaving the wheel the pin touches a fixedly arranged cam path which slides the pin back in the original position, in which position the locking of the pin can be effected again, if desired.

Since, in the known driving mechanism, considerable masses are in motion and in invariably occurring impact of the locking element rotating with the disk against the sloping surface of the magnet armature and the release and locking back of the pin produce annoying sounds. In addition, the mechanism can be used for only one direction of rotation. The known mechanism is thus not suitable for use in film projectors which, in fact, operate at high speeds, must be capable of being driven in either direction of rotation, and in which the occurrence of annoying sounds must be avoided as much as possible. It is the object of the present invention, to improve the known mechanism and make it suitable for use in film projectors of the type in which a film can be projected with a varying number of frames per second.

For this purpose, according to the invention, the new driving mechanism is characterized in that the driving pin is rigidly secured to the disk, and the disk is mounted onthe shaft to be driven continuously so as to be slidable but not rotatable therein. The cam and cam followers control the sliding movement of the disk, and the locking element permits or bars said movement of the disk.

As a result of the measures according to the invention the locking element may be arranged external to the rotating disk, so that the mechanism can operate in either direction of rotation. As a result of the low moving masses the apparatus is suitable for high speeds ,and in addition the occurrence of annoying sounds is reduced considerably.

A suitable embodiment of the invention is characterized 3,456,521 Patented July 22, 1969 in that it comprises an auxiliary shaft which is supported so as to be slidable in the longitudinal direction parallel to the driving shaft and which comprises a radially projecting pin which engages a circumferential curvilinear groove on the circumference of the disk. The auxiliary shaft also has a recess with which the locking element can cooperate to block axial movement of the auxiliary shaft. This construction offers the possibility of a compact structure in the small space available in a projector.

According to the invention the locking element is preferably connected to the magnet armature and supported so as to be rotatable in a plane at right angles to the auxiliary shaft. In this manner the locking element, in the non-operative condition of the magnet, engages the recess of the auxiliary shaft. The driving disk comprises at its circumference a cam which, in the said non-operative condition of the magnet, lifts the locking element with magnet armature out of the recess with every revolution of the disk. As a result of this, the air-gap between the magnet and the armature is reduced with every revolution of the disk which results in a saving of energy for the magnet.

According to the invention, the height of lift of the cam is'preferably chosen such that the magnet armature of the locking element is lifted to abut substantially against the magnet. As a result of this measure, minimum energy consumption of the magnet is required.

In another suitable embodiment of the invention, the driving disk comprises a hub portion, the outer diameter of which is smaller than the outer diameter of the disk. The hub portion is surrounded by a non-rotatable outer sleeve, which engages the disk and is slidable thereon in the axial direction only, while the hub of the disc can freely rotate within this sleeve. The disc is loaded in the axial direction by a spring force which tries to displace the driving pin beyond reach of the Geneva wheel, but this displacement can be checked by the cooperation of the locking element with an abutment surface of the outer sleeve. While in the unlocked condition of the outer sleeve the axial displacement of the pin, disk and sleeve is controlled by the movement of a cam provided on the sleeve along a cam path located around the driving shaft.

In order that the invention may readily be carried into effect, a few examples of the invention will now be described in greater detail, with reference to the drawings, in which FIG. 1 is a side elevation of a mechanism according to the invention,

FIG. 2 is a cross-sectional view of the mechanism taken on the line IIII in FIGURE 1, and

FIG. 3 is a varied embodiment of a driving mechanism according to the invention.

As shown in FIGURES 1 and 2, a driving mechanism according to the invention comprises a disk 1 which is mounted on a shaft 2 to be driven continuously so as to be slidable but not rotatable thereon. The disc also includes an axially projecting eccentric driving pin 3 to drive a Geneva wheel 5 mounted on a shaft 4, the shaft 4 being coupled to film transport members of a film projector not shown. In the position shown, the disk 1 is kept in a position by the springs 6 such that the wheel 5 is normally driven and projecting is carried out, for example, at a rate of 24 frames per second. An auxiliary shaft 7 is supported so as to be slidable in th longitudinal direction parallel to the shaft 2, and comprises a radially projecting pin 8 which engages in a circumferential curvilinear groove 9 on the circumference of the disk 1. The auxiliary shaft 7 comprises a recess 10, the object of which will be explained below.

A locking element 11 to which an armature plate 12 is secured is pivotable about a shaft 13 in a plane at right angles to the auxiliary shaft 7, and is operated by a magnet 14 controlled by electric pulses. The magnet 14 can attract the armature plate 12 with locking member 11, in which case the locking element is lifted out of the recess of the auxiliary shaft 7 and the auxiliary.

shaft is freely slidable. Alternatively the magnet can release the armature plate with locking member, in which case the locking member engages the recess of the auxiliary shaft also under the influence of a spring so that the auxiliary shaft is blocked. In the first case, in which the auxiliary shaft is freely slidable, the pin 8 of the auxiliary shaft will follow the groove 9 in the rotating disk 1 and the normal driving connection between the pin 3 and the wheel 5 and consequently the normal frame speed of 24 frames per second will be maintained. In the second case, in which the auxiliary shaft is blocked, the pin 8 which is now fixed will cause a reciprocating movement of the disk 1 on the shaft 2, which movement is such that the driving pin 3 passes just in front of the wheel 5 so that the film is not transported. During the time that the pin passes in front of the wheel, the Geneva wheel remains blocked on one of its arches by a part 18 of the disk 1.

The disk 1 comprises at its circumference a cam 16 which, when the magnet does not hold the armature plate and the locking element attracted, presses against a projecting part 17 of the locking member with every revolution in such manner that the locking member is lifted out of the recess 10 of the auxiliary shaft. The height of the cam 16 is chosen such that the locking member is lifted to abut substantially against the magnet 14. The magnet which is controlled through an electronic circuit may then hold or release the locking element arbitrarily in accordance with selectively supplied electric pulses. The electronic circuit ensures that the change of the energizing or non-energizing of the magnet takes place during the time that the cam 16 supports the locking element 11, so that the condition can not be varied during one revolution.

The mechanism described enables the number of frames to be projected per second to be varied, while the rate of travel from one frame to the next frame of the film remains equal to the time desired for normal projection so that no annoying flickering of the image occurs. The variation in length of the film loops normally present before and after the. projector aperture occurs when the number of frames to be projected varies. This is normally adjusted by means of toothed rollers, and this adjustment may now be avoided by using the movement of the auxiliary shaft for influencing the rotary movement of the toothed rollers.

FIG. 3 shows a variation of the driving mechanism. In this embodiment the shaft 2 is driven continuously, the disk 1 is provided with the driving pin 3, and is mounted on the shaft 2 so as to be slidable but not rotatable therein, and the shaft 4 has the Geneva wheel 5 secured thereto.

The disk 1 comprises a hub portion 20 th outside diameter of which is smaller than the outside diameter of the disk, so that an abutment surface is obtained. An outer sleeve 21 has a longitudinal groove 22 in which a fixed pin 23 extends from the housing, so that the sleeve is slidable in the axial direction but not. rotatable, and the hub 20 is rotatable in the sleeve. The sleeve also comprises a collar 26 which engages the abutment surface 25 of the disk. A helical spring 24 around the shaft 2 exerts a force on the disk in one direction (in the drawing towards the left) which results in a displacement of the pin 3 beyond reach of the wheel 5. This displacement of the disk with the pin under the influence of the spring force can be prevented by a locking element 27 which is pivotable about the pin 28, whereby spring 29 exerts a force at one end of the element, and a magnet 30 controlled by electric pulses, can exert a counter-acting force on the other end of the element 27.

In the condition shown the magnet 30 attracts the locking element, and the sliding movement of the disk 1 and the outer sleeve 21 is thus prevented by the cooperation of the locking element 27 with the collar 26 of the sleeve. When the magnet releases the locking element, the disc with the sleeve can perform a reciprocating movement in the axial direction which movement is controlled by the cooperation of a cam 31 on the sleeve 21 and a cam path 32 around the shaft 2. As in the preceding example, this cam means produces a movement of the disc such that the driving pin 3 passes just in front of the wheel 5 without engagement. By suitably shaping the cam path 32, the locking element 27 in this embodiment is presented to the magnet 30 with each revolution of the shaft. Dependent upon the fact whether electric pulses are supplied or are not supplied to the magnet 30, the locking may be effected again in the extreme position of the disk 1, in FIG. 3 in the extreme right-hand position.

What is claimed is:

1. A mechanism for providing intermittent rotating output motion from a continuously rotating input, comprising:

(a) a frame,

(b) first and second generally parallel and rotatable shafts mounted on the frame,

(c) an axially slidable control member mounted generally parallel to said shafts,

(d) a disc axially slidable on the first shaft and rotatabl by said input, the disc including a first cam surface disposed around its circumference, and further including an eccentrically disposed axial projection,

(e) a Geneva wheel rotatably carried by said second shaft and drivingly engageable with said axial projection of the disc,

(f) a follower element extending from said control meber for engagement with the cam surface of said disc for relative axial motion with respect to the disc,

(g) control means for selectively (l) contacting and fixing the axial position of the control member whereby the follower element thereof and the cam will drive the disc in a cyclic axial motion, precluding drive engagement with Geneva Wheel, and (2) permitting axial motion of the control member whereby the disc has a fixed axial position and remains in drive engagement with the Geneva Wheel with resultant intermittent rotary motion thereof.

2. A mechanism as defined in claim 1 wherein said control means includes a spring-biased element which urges the disc axially to its engaged position when the control means permits axial motion of the control member.

3. A mechanism as defined in claim 2 wherein said control means further comprises a magnet armature having a locking part which engages and restrains the control member, and an clectromagnet for driving the armature.

4. A mechanism as defined in claim 3 wherein the disc further comprises a second cam surface for cyclically contacting the armature and driving it to be closely adjacent the magnet before each energization thereof, whereby the movement of the armature during the responsive to said energization and the noise of engagement of the magnet and armature are greatly reduced.

5. A mechanism as defined in claim 4 wherein said control member is a rod having a recess therein for engagement with the armature, said follower element is a radially-extending pin, and said mechanism further comprises a second biasing means urging said armature to engage the control member.

6. A mechanism as defined in claim 5 wherein said input drives said first shaft in continuous rotation and the disc is fixedly secured on said shaft for rotation therewith.

7. In a film projector including a continuously rotating output, the improvement in combination therewith comprising a mechanism as defined in claim 1 for providing intermittent motion, the mechanism being driven by said output.

8. A mechanism for providing intermittent rotating output motion from a continuously rotating input, comprising:

(a) a frame,

(b) first and second generally parallel and rotatable shafts mounted on the frame,

(c) a disc including a hub portion and an eccentrically disposed axial projection secured to said first shaft and thereby rotated,

(d) a Geneva wheel rotatably carried by said second shaft and drivingly engageable by said disc projection,

(e) a sleeve mounted on said frame and disposed about said disc hub which is rotatable therein, the sleeve being engaged by the frame for axially slidable but non-rotatable motion with respect to the hub, the hub having an abutting shoulder for engaging a corresponding shoulder of the sleeve and being axially driven in one direction,

(f) spring means urging the disc out of engagement with said Geneva wheel,

(g) cam means carried by said first shaft for engaging and axially driving said sleeve against the hub, and thereby moving the disc to its engaged position with the Geneva wheel, and

(h) control means including an electro-mechanically driven lever operable to engage and maintain the sleeve and disc in said engaged position, said cam means cooperating with the control means to move said lever to its actuated position before the electromagnet is actuated.

References Cited UNITED STATES PATENTS 966,090 8/1910 Hamacek. 2,795,150 6/ 1957 Seidler 74-436 2,870,647 1/ 1959 Lauxen 74-436 3,136,168 6/1964 Matovich 74-436 X 00 LEONARD H. GERIN, Primary Examiner US. Cl. X.R. 

